Flow-accelerated Corrosion Modelling of CANDU Outlet Feeders

Abstract

The primary heat transport system in CANDU reactors is composed of the zirconium alloy in-core components, the carbon steel out-core piping and the Alloy 800 steam generator tubing. The flow- accelerated corrosion (FAC) occurring in the carbon steel outlet feeders at 310°C, because of the undersaturated in dissolved iron there and the high flow rates, dominates and loads the system with magnetite. The FAC is modelled from corrosion mechanisms as the fundamental basis, taking account of electrochemical corrosion potential, oxide film precipitation and dissolution, mass transfer and flow-induced erosion of oxide particles. Good agreement with measurements is obtained.